Mortality rates currently provide our major source of data on the national burden of cancer. In the case of breast cancer, there have been pronounced geographic variations in mortality rates, both at the level of large areas (e.g., the Northeast versus the South) and at the level of small areas (e.g., Long Island versus surrounding areas). Until recently, it has been largely assumed that such variations in mortality rates reflect variations in incidence. There is no doubt that there are important variations in incidence within the United States, both across different populations and different geographic areas. However, in addition to incidence, the other major contributor to mortality rate is survival. Geographic variations in survival with breast cancer is the focus of this proposal. We postulate that variations in survival of breast cancer among older women are responsible in part for the variations in breast cancer mortality. We further hypothesize that these variations in breast cancer survival are secondary to potentially remediable causes, which include stage at diagnosis and treatment received. We have previously shown that older women with breast cancer are more likely to be diagnosed at a more advanced stage and that older women with breast cancer are less likely to receive definitive treatment. The percentage of older women who receive less than definitive treatment varies substantially by region of the country and also by small areas within regions. We propose to use the SEER-Medicare linked data base to examine variation in breast cancer incidence, survival, and mortality by health service area within all SEER sites. The availability of the SEER Medicare data, which can be linked to other data files such as the Area Resource File, will allow us to more completely characterize patient characteristics (age, ethnicity, socioeconomic status at the level of the census tract, etc.), tumor characteristics (size, stage, histology), treatment received (definitive versus non-definitive, chemotherapy, etc.) medical system characteristics (size of hospital, presence of a cancer center, teaching status of hospital, etc.) follow-up surveillance (routine mammography after initial treatment), and outcomes (death, recurrence of cancer, other complications). We can then determine the relative contributions of geographic variations in breast cancer incidence versus variations in breast cancer survival to the observed geographic variations in breast cancer mortality. Furthermore, we can calculate the relative contributions of variations in patterns of breast cancer diagnosis, extent of disease, treatment, population characteristics, and medical system factors to the geographic variations in barest cancer survival.